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Characterization of a Novel Serine Protease Inhibitor Gene from a Marine Metagenome
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, and College of Life Science and Technology, Guangxi University, 100 Daxue East Road, Nanning, Guangxi 530004, China
College of Chemistry and Ecology Engineering, Guangxi University for Nationalities, 188 Daxue East Road, Nanning, Guangxi 530006, China
These authors contributed equally to this work.
* Author to whom correspondence should be addressed.
Received: 2 August 2011; in revised form: 22 August 2011 / Accepted: 25 August 2011 / Published: 5 September 2011
Abstract: A novel serine protease inhibitor (serpin) gene designated as Spi1C was cloned via the sequenced-based screening of a metagenomic library from uncultured marine microorganisms. The gene had an open reading frame of 642 base pairs, and encoded a 214-amino acid polypeptide with a predicted molecular mass of about 28.7 kDa. The deduced amino acid sequence comparison and phylogenetic analysis indicated that Spi1C and some partial proteinase inhibitor I4 serpins were closely related. Functional characterization demonstrated that the recombinant Spi1C protein could inhibit a series of serine proteases. The Spi1C protein exhibited inhibitory activity against α-chymotrypsin and trypsin with Ki values of around 1.79 × 10−8 and 1.52 × 10−8 M, respectively. No inhibition activity was exhibited against elastase. Using H-D-Phe-Pip-Arg-pNA as the chromogenic substrate, the optimum pH and temperature of the inhibition activity against trypsin were 7.0–8.0 and 25 °C, respectively. The identification of a novel serpin gene underscores the potential of marine metagenome screening for novel biomolecules.
Keywords: serine protease inhibitor; uncultured marine microorganisms; sequenced-based screening; functional characterization
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Jiang, C.-J.; Hao, Z.-Y.; Zeng, R.; Shen, P.-H.; Li, J.-F.; Wu, B. Characterization of a Novel Serine Protease Inhibitor Gene from a Marine Metagenome. Mar. Drugs 2011, 9, 1487-1501.
Jiang C-J, Hao Z-Y, Zeng R, Shen P-H, Li J-F, Wu B. Characterization of a Novel Serine Protease Inhibitor Gene from a Marine Metagenome. Marine Drugs. 2011; 9(9):1487-1501.
Jiang, Cheng-Jian; Hao, Zhen-Yu; Zeng, Rong; Shen, Pei-Hong; Li, Jun-Fang; Wu, Bo. 2011. "Characterization of a Novel Serine Protease Inhibitor Gene from a Marine Metagenome." Mar. Drugs 9, no. 9: 1487-1501.